JP4049769B2 - Refrigerant cycle equipment - Google Patents

Description

  In the present invention, a refrigerant circuit is configured by sequentially connecting a compressor, a radiator, a first pressure reducing device, an intermediate pressure receiver, a second pressure reducing device, and an evaporator in a ring shape, and the high pressure side is operated at a supercritical pressure. The present invention relates to a refrigerant cycle device.

  In a conventional refrigerant cycle apparatus of this type, for example, an air conditioner that cools a room, a refrigerant cycle is configured by connecting a compressor, a radiator, a decompressor, an evaporator, and the like in a ring shape. Then, the refrigerant gas is sucked into the compression element of the compressor and compressed to become a high-temperature and high-pressure refrigerant gas, which is discharged and flows into the radiator, where the refrigerant radiates heat. Thereafter, the refrigerant exiting the radiator is throttled by a decompression device and supplied to the evaporator. Therefore, the refrigerant evaporates, and at that time, it absorbs heat from the surroundings to exert a cooling action to cool the room.

Here, in recent years, in order to deal with global environmental problems, even in this type of refrigerant cycle, carbon dioxide (CO ₂ ), which is a natural refrigerant, is used as a refrigerant without using conventional chlorofluorocarbon, and the high pressure side is operated as a supercritical pressure. The device which performs is developed (refer patent document 1).
Japanese Patent No. 2804527

  In this type of refrigerant cycle device, when the temperature of the heat source that exchanges heat with the refrigerant in the radiator rises, the refrigeration effect decreases significantly, so it is necessary to increase the high-pressure side pressure to compensate for it, and as a result, compression There was a problem that the power increased and the performance decreased.

  In addition, since the carbon dioxide refrigerant has a smaller pressure loss than other refrigerants, the degree of decompression in the decompression device must be increased. However, when a normal electronic expansion valve is used as such a decompression device, a desired throttle is required. It was difficult to obtain an effect, and proper control could not be performed.

  On the other hand, when a capillary tube is used as a decompression device, in order to obtain a desired decompression effect, the length of the capillary tube must be increased or the inner diameter must be reduced. In addition, sludge, moisture, and oil are clogged, and there is a risk of disturbing the refrigerant flow. However, in order to obtain a desired pressure reduction effect with a normal capillary tube having an inner diameter of 0.6 mm, the length is 20 m or more.

  The present invention has been made to solve the conventional technical problems, and in a refrigerant cycle device that operates at a supercritical pressure on the high-pressure side, maintenance and improvement of performance, occurrence of clogging, and reduction in size of the capillary tube Plan.

In the refrigerant cycle device of the present invention, a compressor, a first capillary tube, a second capillary tube , an intermediate pressure receiver, an expansion valve and an evaporator are sequentially connected in an annular manner to constitute a refrigerant circuit, and carbon dioxide is used as a refrigerant. The high-pressure side of the refrigerant circuit is operated at a supercritical pressure, and the compressor includes a first compression element and a second compression element that compresses the refrigerant compressed by the first compression element. The gas-phase refrigerant in the intermediate pressure receiver is sucked into the second compression element of the compressor through the check valve, and the liquid-phase refrigerant in the intermediate pressure receiver is decompressed by the expansion valve , and then evaporated. And the inside diameter of the first capillary tube is smaller than the inside diameter of the second capillary tube, and the inside diameter is 0.1 mm or more and 0.4 mm or less .

In the present invention, a compressor circuit, a first capillary tube, a second capillary tube , an intermediate pressure receiver, an expansion valve, and an evaporator are sequentially connected in a ring to form a refrigerant circuit, and carbon dioxide is used as a refrigerant . The high pressure side is operated at a supercritical pressure, and the compressor has a first compression element and a second compression element that compresses the refrigerant compressed by the first compression element. The gas-phase refrigerant in the intermediate pressure receiver is sucked into the second compression element of the compressor through the check valve, and the liquid-phase refrigerant in the intermediate pressure receiver is decompressed by the expansion valve and then introduced into the evaporator. Therefore, the refrigerant flow rate of the first compression element can be reduced to reduce the compression power and improve the coefficient of performance. Moreover, since the refrigerant | coolant flow rate in an evaporator falls, the pressure loss in an evaporator is also reduced and a performance improvement can be aimed at. Furthermore, since the amount of the liquid-phase refrigerant in the evaporator increases, the heat transfer performance is improved, and the overall performance can be improved.

Furthermore, since the inner diameter of the first capillary tube is smaller than the inner diameter of the second capillary tube and the inner diameter is 0.1 mm or more and 0.4 mm or less, the supercritical refrigerant is decompressed by the capillary tube. It will be. Since this supercritical refrigerant has excellent dissolution characteristics, clogging with sludge, moisture, and oil is less likely to occur even if the inner diameter of the capillary tube is reduced to 0.1 mm or more and 0.4 mm or less. Accordingly, even when carbon dioxide is used as a refrigerant and the degree of decompression must be increased, the length of the capillary tube can be shortened to improve the space efficiency.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a refrigerant circuit diagram of a refrigerant cycle device 210 according to an embodiment of the present invention. The refrigerant cycle device 210 of the present embodiment includes a compressor circuit, a radiator 12, a first pressure reduction device 13, an intermediate pressure receiver 16, a second pressure reduction device 17, and an evaporator 20, which are sequentially connected in a ring shape to form a refrigerant circuit. It is configured. That is, the refrigerant discharge pipe 10 </ b> A of the compressor 10 is connected to the inlet of the radiator 12.

  Here, the compressor 10 of the embodiment is a two-stage compression type compressor having a first compression element 30 and a second compression element 32 that compresses the refrigerant compressed by the first compression element 30. A driving element and a first compression element 30 and a second compression element 32 driven by the driving element are provided in an airtight container (not shown).

  11 in the figure is for discharging the refrigerant compressed by the first compression element 30 (first stage) of the compressor 10 to the outside of the sealed container and introducing it into the second compression element 32 (second stage). It is a refrigerant introduction pipe. A communication pipe 40 which will be described later is connected to the middle part of the refrigerant introduction pipe 11.

In addition, the refrigerant pipe 12 </ b> A exiting the radiator 12 is connected to the inlet of the first decompression device 13. Here, the first decompression device 13 includes a first capillary tube 14 and a second capillary tube 25 , where the first capillary tube 14 is upstream of the refrigerant and the second capillary tube 25 is the first capillary. It arrange | positions so that it may become the downstream of the tube 14. FIG. That is, the refrigerant radiated by the radiator 12 is decompressed by the first capillary tube 14 provided on the upstream side by the first decompression device 13, and then the second capillary tube 25 provided on the downstream side thereof. The pressure is reduced at. The first capillary tube 14 has an inner diameter of 0.1 mm to 0.4 mm and a dimension of 0.5 m to 5 m.

On the other hand, the refrigerant pipe 15 </ b> A connected to the outlet side of the first pressure reducing device 13 reaches the inlet of the intermediate pressure receiver 16. The intermediate pressure receiver 16 is for separating the gas-liquid refrigerant, and the refrigerant that has been decompressed by the first decompression device 13 to become a gas / liquid two-phase mixture is supplied to the intermediate pressure receiver 16. Thus, the liquid phase refrigerant is temporarily stored in the intermediate pressure receiver 16. Above the intermediate pressure receiver 16, the communication pipe 40 described above is connected. This communication pipe 40 is for returning the gas-phase refrigerant separated from the liquid phase by the intermediate pressure receiver 16 to the compressor 12. The refrigerant introduction pipe 11 direction is a forward direction in the middle of the communication pipe 40. A check valve 42 is provided. As a result, the gas-phase refrigerant separated from the liquid-phase refrigerant by the intermediate pressure receiver 16 passes through the communication pipe 40, reaches the refrigerant introduction pipe 11 of the compressor 12, and is compressed by the first compression element 30. It merges with the intermediate-pressure refrigerant gas and is sucked into the second compression element 32.

  On the other hand, a refrigerant pipe 16A reaching the inlet of an electronic expansion valve 17 as a second decompression device is connected to the bottom surface of the intermediate pressure receiver 16, and is separated from the gas phase refrigerant by the intermediate pressure receiver 16 once. The stored liquid phase refrigerant flows from the refrigerant pipe 16A to the expansion valve 17. A pipe 17 </ b> A exiting the expansion valve 17 is connected to the inlet of the evaporator 20.

  And the refrigerant | coolant inlet tube 20A of the said compressor 10 is connected to the exit side of the evaporator 20, and the cyclic | annular cycle which returns to the compressor 10 is comprised.

As the refrigerant of the refrigerant cycle device 210 , which is friendly to the global environment, carbon dioxide (CO ₂ ), which is a natural refrigerant, is used in consideration of flammability and toxicity, and the oil as the lubricating oil is PAG (polyalkylene glycol), POE (polyol ester) or the like is used.

Next, the operation of the refrigerant cycle apparatus 210 will be described with reference to the ph diagram (Mollier diagram) of FIG. When a drive element (not shown) of the compressor 10 is driven by a control device (not shown), a low-pressure refrigerant gas is sucked into the first compression element 30 of the compressor 10 (state A in FIG. 2) and compressed to be intermediate. Pressure refrigerant gas (state B in FIG. 2). The intermediate-pressure refrigerant gas is sucked into the second compression element 32 through the refrigerant introduction pipe 11. At this time, the refrigerant gas at the intermediate pressure is lowered in temperature by the joining of the gas-phase refrigerant from the intermediate pressure receiver 16, which will be described later, and becomes the state of C in FIG. The refrigerant sucked into the second compression element 32 is compressed in the second stage to become high-temperature and high-pressure refrigerant gas, and is discharged to the outside through the refrigerant discharge pipe 10A. At this time, the refrigerant is compressed to an appropriate supercritical pressure (about 7 MPa at the time of rating, but varies from 5 MPa to 11 MPa depending on environmental conditions) (state D in FIG. 2).

  The refrigerant gas discharged from the refrigerant discharge pipe 10A flows into the radiator 12, where it dissipates heat by an air cooling method or a water cooling method. In the heat radiator 12, the carbon dioxide refrigerant is condensed and the temperature is lowered to a state E in FIG.

The refrigerant radiated by the radiator 12 reaches the first pressure reducing device 13 through the refrigerant pipe 12A. In the first decompression device 13, the refrigerant first flows into the first capillary tube 14 provided on the upstream side, and the pressure decreases in the process of passing through the capillary tube 14 (state F in FIG. 2). .

Here, since the refrigerant exiting the radiator 12 is in a supercritical state as described above, the refrigerant remains in the supercritical state in the capillary tube 14 or in the vicinity of the outlet of the capillary tube 14 in the gas phase / liquid state. By only becoming a two-phase mixture of phases, the pressure is reduced while maintaining the supercritical state in most of the strokes passing through the first capillary tube 14.

Such supercritical refrigerants have excellent dissolution characteristics. For this reason, even if the inner diameter of the first capillary tube 14 is reduced to 0.1 mm or more and 0.4 mm or less, clogging due to sludge, moisture, or oil hardly occurs.

  When using conventional chlorofluorocarbon refrigerants, the capillary tube usually has an inner diameter of about 0.6 mm. If the inner diameter is reduced further, sludge, moisture, oil, etc. are clogged and the refrigerant flow is hindered. There was a fear.

However, using carbon dioxide as a refrigerant, by refrigerant pressure entering the first capillary tube 14 to a supercritical state, it becomes possible to depressurize the refrigerant in the supercritical state in the first capillary tube 14 Due to the excellent melting characteristics peculiar to the supercritical state, the inner diameter of the first capillary tube 14 can be reduced to 0.1 mm or more and 0.4 mm or less. Thereby, even if a carbon dioxide refrigerant with a small pressure loss is used, the inconvenience of disturbing the refrigerant flow is avoided, the size of the first capillary tube 14 is reduced, and the throttling effect in the first capillary tube 14 is reduced. You can get enough.

As a result, even when carbon dioxide is used as a refrigerant and the degree of decompression must be increased, the length of the first capillary tube 14 can be shortened to improve the space efficiency.

The refrigerant depressurized by the first capillary tube 14 is then supplied to a second capillary tube 25 (inner diameter is 0.5 mm or more and 0.6 mm or less, the dimension is provided downstream of the first capillary tube 14) . 2) , and a gas / liquid two-phase mixture is formed by the pressure drop in the second capillary tube 25 (state G in FIG. 2). ) To the intermediate pressure receiver 16. In the intermediate pressure receiver 16, the pressure of the refrigerant is reduced to about 3 MPa to 4 MPa due to the pressure reducing effect in the first pressure reducing device 13. Then, in the intermediate pressure receiver 16, the refrigerant is separated into a gas phase refrigerant (saturated vapor) and a liquid phase refrigerant (saturated liquid), and the gas phase refrigerant enters the state H in FIG. Then, the refrigerant is returned to the refrigerant introduction pipe 11 of the compressor 10 and merged with the intermediate pressure refrigerant compressed by the first compression element 30. At this time, the refrigerant is in the state shown in FIG.

  In this way, the gas-liquid of the refrigerant is separated by the intermediate pressure receiver 16 and the gas component is returned from the communication pipe 40 to the refrigerant introduction pipe 11 of the compressor 12, so that the gas component that does not contribute to cooling is removed from the intermediate pressure receiver 16. The efficiency of the refrigerant cycle can be improved by this amount without circulating to the low pressure side refrigerant circuit thereafter. In particular, by using carbon dioxide refrigerant as in the present invention, the amount of gas-phase refrigerant separated by the intermediate pressure receiver 16 is larger than that of conventional chlorofluorocarbon-based refrigerant, and the gas-phase refrigerant is used as the refrigerant introduction pipe 11 of the compressor 10. Therefore, the efficiency can be further improved.

  On the other hand, the liquid phase refrigerant is temporarily stored in the intermediate pressure receiver 16 to be in the state of I in FIG. Thus, the state of J in FIG.

  The refrigerant whose pressure has been reduced by the expansion valve 17 flows into the evaporator 20 through the pipe 17A. Therefore, the refrigerant evaporates, and at that time, the refrigerant absorbs heat from the surroundings and exhibits a cooling action.

  Thereafter, the refrigerant exiting the evaporator 20 repeats the cycle of being sucked into the first compression element 30 from the refrigerant introduction pipe 20A of the compressor 10 (state A in FIG. 2).

  In this way, the intermediate pressure receiver 16 causes the gas-phase refrigerant to be sucked into the second compression element 32 of the compressor 10, and the liquid-phase refrigerant in the intermediate pressure receiver 16 is expanded by the expansion valve 17 as the second decompression device. Since the pressure is reduced and then introduced into the evaporator 20, the refrigerant flow rate of the first compression element 30 can be reduced. Thereby, the compression power in the 1st compression element 30 can be reduced, and a coefficient of performance can be improved.

  Moreover, since the refrigerant | coolant flow rate in the evaporator 20 falls, the pressure loss in the evaporator 20 is also reduced and the performance can be improved.

  Furthermore, since the amount of the liquid-phase refrigerant in the evaporator 20 increases, the heat transfer performance is improved and the performance can be improved as a whole.

The second decompression device is not limited to the electronic expansion valve as in the above embodiment, and for example, the second decompression device may be constructed with a conventional capillary tube as shown in FIG. .

FIG. 3 is a refrigerant circuit diagram of the refrigerant cycle device 410 in this case, and 27 is a capillary tube as a second decompression device. In FIG. 3 , the same reference numerals as those in FIG. 1 denote the same or similar effects.

Also in this case first a supercritical refrigerant, by vacuum in the first capillary tube 14 inner diameter small, it is possible to sufficiently decompressing the refrigerant, a second capillary tube 25 on the downstream side of A conventional capillary tube can be used without reducing the inner diameter or enlarging the dimensions.

In each of the above-described embodiments, the refrigerant is evaporated by one evaporator 20, but a plurality of evaporators may be arranged in parallel to cause the refrigerant to flow through each of the evaporators to be evaporated. In this case, for example, as shown in FIG. 4 , a branch pipe 16B is connected to the middle of the pipe 16A, and a capillary tube 28 and an evaporator 21 are provided in the branch pipe 16B. Further, it is assumed that the branch pipe 21 </ b> A exiting from the evaporator 21 is connected to the middle part of the refrigerant introduction pipe 20 </ b> A connected to the outlet side of the evaporator 20. Furthermore, the branch pipe 21A on the outlet side of the evaporator 21 is provided with a check valve 24 whose forward direction is the refrigerant introduction pipe 20A side. Similarly, the refrigerant introduction pipe 20A has a reverse direction whose forward direction is the compressor 10 side. A stop valve 22 is installed. Then, a three-way valve 19 is provided at the connection position of the branch pipe 16B, and the three-way valve 19 allows the liquid-phase refrigerant separated from the gas-phase refrigerant by the intermediate pressure receiver 16 to flow into the capillary tube 27 or to the capillary tube 28. The refrigerant can be selectively evaporated in each of the evaporators 20 and 21 by appropriately controlling whether to flow or to both.

  As a result, when the refrigerant cycle device 510 is used as an air conditioner for air-conditioning the room, the two rooms can be selectively cooled by the evaporators 20 and 21. Further, when the refrigerant cycle device 510 is applied to a refrigerator or the like, two different cooling spaces can be simultaneously or selectively cooled. Thereby, the versatility of the refrigerant cycle device can be improved.

It is a refrigerant circuit figure of the refrigerant cycle device of one example of the present invention. It is a ph diagram of the refrigerant cycle device of FIG. It is a refrigerant circuit figure of the refrigerant cycle device of the 2nd example of the present invention. It is a refrigerant circuit figure of the refrigerant cycle device of the 3rd example of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Compressor 11, 20A Refrigerant introduction pipe 12 Radiator 12A, 15A, 16A, 17A Refrigerant piping 13 First decompression device 14, 25, 27, 28 Capillary tube 15, 17 Electronic expansion valve 16 Intermediate pressure receiver 19 Three-way valve 20, 21 Evaporator 22, 24, 42 Check valve 30 First compression element 32 Second compression element 40 Communication pipe
210, 410, 510 refrigerant cycle apparatus

Claims (1)

A compressor circuit, a first capillary tube, a second capillary tube , an intermediate pressure receiver, an expansion valve, and an evaporator are sequentially connected in an annular manner to form a refrigerant circuit. Carbon dioxide is used as a refrigerant, and the high pressure side of the refrigerant circuit is supercritical. Operated with pressure,
The compressor has a first compression element and a second compression element which compresses a refrigerant compressed by the first compression element, the check valve to the gas-phase refrigerant in the intermediate pressure receiver And sucking into the second compression element of the compressor through the pressure reduction of the liquid phase refrigerant in the intermediate pressure receiver in the expansion valve , and then introduced into the evaporator,
A refrigerant cycle device characterized in that an inner diameter of the first capillary tube is smaller than an inner diameter of the second capillary tube, and the inner diameter is 0.1 mm or more and 0.4 mm or less .

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